document.write( "Question 1003187: I would like to know the formula for this sequence 1, 3, 12, 48 \n" ); document.write( "
Algebra.Com's Answer #620044 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
1, 3, 12, 48
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document.write( "If we ignore the 1, and look at the next three terms,\r\n" );
document.write( "we can see that they form a geometric series with\r\n" );
document.write( "common ratio 4.  But the first term would have to be\r\n" );
document.write( "3/4, not 1.  It would be easy to find a formula for\r\n" );
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document.write( "3/4, 3, 12, 48 \r\n" );
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document.write( "an = ceiling(3*4^(n-2))\r\n" );
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document.write( "But hey!, we can make 3/4 become 1 by rounding it up to the\r\n" );
document.write( "next integer.  Since all the other terms are integers,\r\n" );
document.write( "we can simply use the the ceiling or \"round up\" function, as\r\n" );
document.write( "it does not affect integers.  The ceiling function is usually \r\n" );
document.write( "denoted by a square bracket with the bottom part missing.  \r\n" );
document.write( "I'll just indicate it on here by \"ceiling( )\"\r\n" );
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document.write( "So a formula is\r\n" );
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document.write( "an = ceiling(3*4^(n-2))\r\n" );
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document.write( "Edwin
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